I guess it will be out of scope, since coolreader for the Kindle is standing on the shoulders of giants - i.e. the CRengine (it is also used in kindlepdfviewer, thus I know it a bit). That again uses the antiword engine to read those files. And this does only "classic" DOC/RTF. The newer formats like docx and odt are quite a bit different.

Then, "better than X because it is generated by Y" is not really an argument, but more "politics". You certainly know that OpenOffice/LibreOffice will also happily create DOC, right? It's not their native format, that's right.